Effect of coloring liquids on color of zirconia frameworks and bond strength of zirconia/veneering ceramic

Effects of Coloring Liquid Dipping Time and Surface Finishing Procedures on the Optical Properties of Monolithic Zirconia

BACKGROUND

Monolithic zirconia restorations can be produced from self-colored or uncolored blocks. The coloring procedure of uncolored blocks and surface treatments may affect the appearance of the restoration.

AIM

The purpose of this study is to evaluate the effect of liquid coloring and surface treatments on optical properties of translucent monolithic zirconia.

METHODS

All specimens were cut from zirconia blocks with a thickness of 1 mm. Specimens were dipped in the coloring liquids for 3 min, 5 min, and 7 min and then divided into groups of 10 specimens for surface treatments. Glaze and mechanical polishing were applied, and the color of the specimens was measured under the D65 lighting condition with a spectrophotometer device. Color values obtained from the CIE Lab formula and the translucency parameter (TP), opalescence parameter (OP), and contrast ratio (CR) were calculated. The normality of the data was confirmed with the Shapiro-Wilk test. A three-way analysis of variance (ANOVA) was used to assess the effect of dipping time, liquid shade, and surface treatments.

RESULTS

The effect of liquid shade and dipping time on the TP, OP, and CR parameters were statistically significant, and the TP values were reduced with the application of coloring liquid. Mechanical polishing groups had higher OP values and lower TP values than glazed groups.

CONCLUSION

In cases where high translucency is required, it may be advisable to use self-colored blocks and apply glaze as a surface treatment to achieve the desired optical properties.

The Effect of Sintering Procedures on Fit and Color in Zirconia Crowns

Purpose:

The aim of this study was to examine the effects of various sintering procedures on the color parameters, marginal, and internal fit of zirconia crowns.

Materials and Methods:

Overall, 60 zirconia crowns were produced using 3 distinct zirconia blocks (Wieland Zenostar, Zirkonzahn Ice Translucent, and Zirkonzahn Prettau). For the sintering procedure of the crowns, six groups were created as follows: Wieland-Standard, Wieland-Speed, Ice-Standard, Ice-Speed, Prettau-Slow, and Prettau-Standard programs. The crowns were assigned into groups ( n = 10 in each group). The color parameters, marginal fit, and internal fit of the crowns were evaluated. The normality of data distribution was evaluated with the Kolmogrov–Smirnov test. Two independent samples t-test and Mann–Whitney U test were used to compare the sintering groups.

Results:

Acceleration of sintering caused a significant change in the color parameters of the Wieland and Ice groups but not in the Prettau group. In the Wieland group, marginal ( p = .047) and internal ( p = .004) gap values of speed sintering were found to be significantly lower than those in standard sintering. In the Ice group, the marginal gap values of speed sintering were found to be significantly lower than those in standard sintering ( p = .019). In the Prettau group, the marginal gap values of standard sintering were found to be significantly higher ( p = .035) than those in slow sintering.

Conclusions:

It was concluded that the effects of sintering procedures on color parameters, and internal and marginal fit of zirconia crowns were clinically insignificant. Speed sintering can be recommended for zirconia restorations.